THS3120_14 Datasheet, PDF (16/36 Pages) Texas Instruments – LOW-NOISE, HIGH-OUTPUT DRIVE, CURRENT-FEEDBACK OPERATIONAL AMPLIFIERS

THS3120
THS3121
SLOS420E – SEPTEMBER 2003 – REVISED OCTOBER 2009........................................................................................................................................ www.ti.com
WIDEBAND, INVERTING OPERATION
Figure 48 shows the THS3121 in a typical inverting
gain configuration where the input and output
impedances and signal gain from Figure 47 are
retained in an inverting circuit configuration.
50 Ω Source _RG
V_I
340 Ω
R_M
59 Ω
15 V _+VS
0.1 µF
+
6.8 µF
+
T_{_}HS3120
49.9 Ω
50 Ω LOAD
R_F
681 Ω
0.1 µF 6.8 µF
+
-15 V ^-VS
Figure 48. Wideband, Inverting Gain
Configuration
SINGLE-SUPPLY OPERATION
The THS3120 and THS3121 have the capability to
operate from a single supply voltage ranging from
10 V to 30 V. When operating from a single power
supply, biasing the input and output at mid-supply
allows for the maximum output voltage swing. The
circuits of Figure 49 show inverting and noninverting
amplifiers configured for single-supply operation.
+V_S
50 Ω Source
+
V_I
R_T
49.9 Ω
THS3120
_
+V_S
2
R_F
R_G
649 Ω
649 Ω
+V_S
2
50 Ω Source
R_G
V_I
59 Ω
340 Ω
R_T
R_F
681 Ω
V_S
_
THS3120
+
+V_S +V_S
2
2
49.9 Ω
50 Ω LOAD
49.9 Ω
50 Ω LOAD
Figure 49. DC-Coupled, Single-Supply Operation
Video Distribution
The wide bandwidth, high slew rate, and high output
drive current of the THS3120 and THS3121 matches
the demands for video distribution for delivering video
signals down multiple cables. To ensure high signal
quality with minimal degradation of performance, a
0.1-dB gain flatness should be at least 7x the
passband frequency to minimize group delay
variations from the amplifier. A high slew rate
minimizes distortion of the video signal, and supports
component video and RGB video signals that require
fast transition times and fast settling times for high
signal quality.
649 Ω
649 Ω
15 V
-
V_I
+
-15 V
75 Ω
75-Ω Transmission Line
75 Ω
V_O(1)
n Lines
75 Ω
75 Ω
V_O(n)
75 Ω
Figure 50. Video Distribution Amplifier
Application
16
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